Rear Admiral Grace Murray Hopper ’34 Ph.D., known affectionately as “Amazing Grace,” would have been 109 years old today. Inventor of the first computer compiler, she was a pioneer of women in STEM (science, technology, engineering, and math), and her impact can still be felt in computer science.

“Much of the essence of computer programming as we know it, from subroutines to machine-independent languages, was conceived by Grace Murray Hopper. She was a true pioneer,” said Joan Feigenbaum, chair of the Department of Computer Science. “Amazing Grace was a hero, not only technically but personally, socially, and organizationally. I am so deeply honored to be Yale’s inaugural Grace Murray Hopper Professor of Computer Science.”

The oldest of three children, Hopper was born in New York City to an upper middle-class family. Her father, Walter Fletcher Murray, graduated from Yale Phi Beta Kappa in 1894 and owned an insurance company. Her mother, Mary Campbell Van Horne, though never formally trained, also shared a love for mathematics. Both encouraged intellectual curiosity in their children and made sure their home was filled with books.

When Hopper was 7 years old, she took apart every single alarm clock in the house because she wanted to learn how they worked. Instead of being reprimanded, Hopper’s mother limited her to one alarm clock. Hopper would warmly recount the story throughout her life as an example of her inquisitive character.

In 1928, she graduated Phi Beta Kappa from Vassar College with a degree in mathematics and physics, joining the Vassar faculty after graduation. She continued her studies at Yale, earning her M.A. in 1930 and her Ph.D. in 1934, both in mathematics. Earning a doctorate in mathematics was a rare accomplishment for women at the time.

During her time at Yale, she met Vincent Foster Hopper, an English teacher in New York, and they married in 1930. Although they separated in the early 1940s, she would keep his name for the rest of her life.

Hopper continued teaching at Vassar until 1943 when she decided to join the Navy. She had been deeply moved by the attack on Pearl Harbor in 1941 and wanted to serve in the Navy like her great-grandfather had done. Despite being told she was too old and too small to join, she persevered and was able to join the Navy Reserves in December 1943 after obtaining a waiver for her weight.

She was assigned to the Computation Project of the Bureau of Ships at Harvard University and began working on the MARK I computer with Howard Aiken. The MARK I was 51 feet long and 8 feet tall with 500 miles of wiring, and was the Navy’s most advanced computer, capable of completing three operations in a second.

Hopper’s notes with the “bug” found inside the MARK II. (Photo courtesy of Navy website)

After the war ended, Hopper stayed in the Navy and at Harvard to work on the MARK II and III computers. During this time, she popularized the terms “bug” for a problem in computer code and “debugging,” the method of fixing glitches, when she found a moth inside the MARK II.

In 1949, she left Harvard to join the Eckert–Mauchly Computer Corporation, joining the team that developed the UNIVAC I, the first commercial computer in the United States. In 1952, she completed her first compiler, the A-0 (Arithmetic Language version 0). Hopper had compiled all the subroutines she had collected and put them on tape with different call numbers. The A-0 system allowed the user to specify the call numbers of the desired routines, and the computer would locate them on the tape and execute the command.

“I had a running compiler and nobody would touch it, because, they carefully told me, computers could only do arithmetic, they could not write programs,” she recalled in an interview with the New York Times in 1986. “It was a selling job to get people to try it. I think with any new idea, because people are allergic to change, you have to get out and sell the idea.”

She continued working on the compiler, developing the A-1 and A-2 systems. One of Hopper’s core beliefs was making computer language more accessible to the general public by writing code in English. Defying skeptics who believed that computers could not “understand English,” she invented the FLOW-MATIC (B-0) programming language in 1957.

FLOW-MATIC was created for business data processing applications and was notable for using English-like instructions. Hopper’s compilers and her ideas on using language close to English served as the foundation for COBOL (Common Business Oriented Language), the most widely used computer language of the 20th century.

Although she retired from the Navy in 1966 due to age, she quickly rejoined the next year to help standardize its programming languages. By the time she retired permanently in 1986, she was the oldest officer on active duty with the rank of rear admiral and the first woman to achieve the rank in U.S. Navy history.

Hopper earned numerous awards during her life for her achievements in computer science and in the Navy. In 1969, she was awarded the first ever Computer Science Man-of-the-Year Award from the Data Processing Management Association. In 1973, she became the first person from the United States and the first woman of any nationality to be made a Distinguished Fellow of the British Computer Society. In 1991, President George Bush awarded her the National Medal of Technology, making her the first woman to earn the accolade.

According to J.A.N. Lee’s “Computer Pioneers,” despite all her awards, Hopper frequently said that she was proudest of “all the young people I’ve trained over the years — that’s more important than writing the first compiler.” Hopper passed away in her sleep on Jan. 1, 1992 at her home in Arlington.

In celebration of Hopper’s 109th birthday, Lisa Brandes, assistant dean for student affairs and director of the Office of Graduate Student Life, helped organize a “Cupcakes and Coding” event on Dec. 3 along with graduate students from Women in Science at Yale (WISAY) and the Society of Women Engineers (SWE).

“In the Graduate School of Arts & Sciences (GSAS), we are pleased to celebrate our own amazing alumna, Admiral Grace Hopper, who did so much to start computing and coding, and to serve her country,” Brandes said. “Plus as a GSAS alumna myself, I’m in awe of her accomplishments as a great pioneer for women in STEM fields.”